Weeks or months later, when the brain is relaxed, the scalp well healed and the patient's medical condition permits, the individual is taken back to the operating room and the bone is reimplanted (A procedure known as an autologous cranioplasty). The aim of the procedure is to restore cosmesis and protection to the underlying brain and it can sometimes also improve neurological symptoms by unknown mechanisms. Unfortunately these aims are not always achieved and whilst technically straightforward the procedure is known to be associated with a number of complications. Two of the most significant of these are infection (such that the bone flap needs to be removed and replaced) and resorption (such that the protective function is compromised). Overall 10% of autologous bone patients become infected, 10% require replacement due to resorption and 12% become significantly resorbed, then in 32% of case the autologous bone has failed.